1. Field of the Invention
This invention relates to improvements in an air intake structure of an automobile.
2. Description of Related Art
A vehicle body structure of the automobile contains a cowl frame structure extending in a transverse direction of the vehicle body as one of vehicle body strengthening members.
The cowl frame structure consists of an upper member portion and a lower member portion, and positioned between a dash panel constituting a forward wall member of the vehicle chamber and front glass window. The upper member portion of the cowl frame supports the bottom portion of the front glass window, and the lower member portion thereof connects the upper member portion to the upper portion of the dash panel. The cowl frame structure generally functions as an air intake structure that introduces outside air into the vehicle chamber.
Japanese Utility Model Publication (laid-open) No. 82,881/1986 discloses a cowl frame structure having a closed cross section such that one of air inlets for introducing outside air into the vehicle chamber is provided on the upper member portion of the cowl frame structure while the other is disposed on the lower member portion thereof. The air inlets are communicated with each other through an air passage disposed in an interior space of the cowl frame structure.
There is another type of a cowl frame structure having such a cross section having an opening in a forward direction. This cowl frame structure is provided with one air inlet disposed on the upper member portion of the cowl frame structure and the other air inlet on the lower member portion thereof in such a manner that the two air inlets are connected to each other through a duct disposed in a space interposed between the upper and lower member portions thereof.
There is the recent tendency that they have a preference for designs of the vehicle body which consider air characteristics. A known representative method of decreasing a resistance of air flowing from the front side of the vehicle body is to decrease a forward surface area of projection by sharpening an inclined angle of the front glass window W with the bonnet B as a front hood, as shown in FIG. 13.
However, such designs on the vehicle body may cause the problem that, as an inclined angle of the front glass window W intersected with the bonnet B gets sharper, a cowl point P intersecting the window glass W with the cowl frame structure becomes lower. As a result, the difficulties may arise in ensuring spaces for location of an air conditioning unit and for placement of the legs of the operator and passenger. Referring further to FIG. 13, a space interposed between the cowl point P and a floor surface F of the vehicle chamber is used for mounting air passage A and the air conditioning unit U, and as a legs placing space S. For the air passage A, it is necessary to ensure a predetermined crosssectional area in order to provide a sufficient amount of outside air into the vehicle chamber R. Accordingly, the lower the position of the cowl point P, the more difficult it is to ensure a sufficient height in the space for mounting the air conditioning unit U and the legs placing space S. In order to avoid such difficulties, it is possible to permit a thinner structure of the air passage A disposed in the cowl frame structure while making its transverse size wider to compensate for a space reduced by lowering the cowl point P, thus ensuring a necessary space for mounting the air conditioning unit U and placing the legs of the driver and passenger. This structure of the air passages A, however, provides the drawbacks that the cowl frame structure protrudes into the vehicle chamber R or into the engine room A, thereby producing big limit to a layout of instrument panels or the engine room E.
Conventional air intake structures have one of the air inlets on the forward portion of the cowl frame structure so that it is advantageous to allow the air to be introduced during driving. However, since this arrangement may undergo a direct influence from kinetic pressures during the driving, it may permit rainfall to be introduced together with the air into the air passage, thus enabling the rainfall to be penetrated into the air conditioning unit through the other air inlet for introducing outside air into the vehicle chamber.
In order to prevent a leakage of rainfall into the vehicle chamber, the current meassure adopted by conventional air intake structure is merely that the air passage to be formed in the cowl frame structure is rendered as long as possible.
The demands that the air passage should be rendered longer in the cowl frame structure and a sufficient amount of outside air should be introduced into the vehicle chamber lead to the consequence that the cowl frame structure should be larger in cross sectional area over a considerable length where a sufficient space is required for ensuring the mounting of the air conditioning unit and the placement of the legs of the driver and passenger.